Diets that promise rapid weight loss but may have only short-term effects
People who are overweight often look for a quick way to lose weight and many are keen to try any new diet that appears on the market. There are new diets coming out all the time, each with its own unique formula, promising easy and rapid weight loss. A fad diet is a weight loss plan that gives this type of quick fix. However, most of these diets do not provide a long-term solution to the problem of excess weight.
What are the types?
Fad diets that promise quick weight loss usually recommend only a particular food or type of food. They are popular because many of them work for a short time. They ensure that a person following the diet takes in fewer calories than he or she normally would because he or she stops eating certain types of food or eats combinations of specific food that are part of the diet’s formula. However, much of the weight lost is not from body fat, but from water and lean muscle.
High protein–low carbohydrate diets
People following these diets often lose weight very rapidly. However, the weight loss is not sustained once the diets are discontinued. A high fat intake may increase the risk of heart disease. Nutritionists recommend animal proteins such as lean chicken and fish, and plant proteins such as nuts and beans, but advise against cutting out whole groups of foods, such as starchy carbohydrates, or limiting the consumption of fruit and vegetables.
These diets are based on the belief that different food types are digested in different ways and should not be eaten together in the same meal. For example, carbohydrates and proteins should not be combined in a meal. However, food-combining diets can be unbalanced and unhealthy. Each of the five components in a balanced diet – carbohydrates, fats, proteins, vitamins, and minerals – contributes to health and it is important that they are consumed in correct proportions (see A healthy diet).
Liquid meal replacement diets
These very low-calorie diets result in rapid weight loss. They can be effective and nutritionally balanced, and may help to motivate people to change their diet and lifestyle. However, they should be followed only for short periods. People on meal-replacement diets may find it difficult to maintain a lower weight if they return to their previous eating habits. If you are pregnant or breast-feeding, have health problems, or wish to lose a large amount of weight, consult your doctor before starting.
Diets that emphasize one particular food are based on very low-calorie foods such as cabbage. The extremely low calorie intake may cause the depletion of body muscles, including the heart muscle, and upset your blood glucose levels. These diets may be lacking in one or more essential food components and may therefore cause nutritional deficiencies.
What are the risks?
Fad diets often involve theories that lack adequate scientific support, such as the belief that carbohydrates are fattening and protein foods help in slimming. In fact, a balanced diet with less fat, adequate amounts of carbohydrates, and a limited calorie intake will help people to lose weight in a more controlled way, especially when combined with plenty of exercise.
A high-fat diet is more likely to result in over-consumption of calories than a high-carbohydrate diet. This is because fat contains almost twice the amount of calories as carbohydrates. For example, 1 g of fat has 9 calories while 1 g of carbohydrate contains 4 calories. Therefore, it is much more sensible to follow a diet that has less fat than carbohydrates, so that weight loss is gradual and easier to maintain.
Repeated episodes of rapid loss of weight while on a fad diet are often followed by weight gain (the “yo-yo” effect). This can cause people to gain even more excess weight than they had originally and may lead to a sense of failure and depression.
Health risks include wasting of the body’s muscle mass, including the heart muscle. Fad diets can also cause nutritional deficiencies. For example, iron deficiency may cause anaemia and calcium deficiency may aggravate the disorder osteoporosis, in which there is a loss of bone density. In addition, a lack of vitamins in the diet may lead to deficiency diseases which may affect physical and mental wellbeing. For example, a vitamin D deficiency may result in poor absorption of calcium from the diet, which leads to weakening and softening of the bones.
It is important to assess the diet you choose to follow. People who need to take special care are children, adolescents, women who are pregnant or breast-feeding, the elderly, those with conditions such as diabetes mellitus or those who have heart, kidney, or musculoskeletal problems.
What might be done?
The only effective way to lose weight is to plan a weight-loss programme that involves a gradual and long-term change in eating habits and exercise. If you wish to lose weight, you should consult your doctor. He or she can help you to plan your weight loss in a safe and effective way. You should eat a variety of foods, such as whole grains, pulses, vegetables, and fruit, but in limited quantities. You should never skip a meal, but limit your intake of saturated fats and sugar. You should also be more physically active in your everyday life, and make a concerted effort to exercise regularly (see Exercise and health). Losing weight means taking in fewer calories relative to energy expenditure in a sustained way. There are no quick and easy solutions.
From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.
The subjects, conditions and treatments covered in this encyclopaedia are for information only and may not be covered by your insurance product should you make a claim.